Tailored TiO2 nanostructures for designing of highly efficient dye sensitized solar cells: A review

Energy and the environment are two major challenges for our modern civilization and solar energy plays an important role among the renewable energy alternatives due to its availability and eco-friendly nature. One of the prominent routes for the conversion of solar energy into electrical energy is photo-voltaic technology. The dye sensitized solar cell (DSSC) has emerged as one of the promising technologies among photo-voltaic solar cells due to its eco-friendly nature and cost effectiveness, being fabricated from specific components such as a photoanode, photo-sensitizer dye, electrolyte and counter electrode. Recent developments in various components of dye sensitized solar cells (DSSCs) have improved their performance under both solar sunlight (power conversion efficiency (PCE) ∼ 15%) and ambient light conditions (PCE ∼ 34%), with long term operational stability. The photoanode plays a vital role in developing a proficient DSSC and the tailoring of photoanodes is observed as one of the opportunities for world scientific communities to make further improvements in the PCE. For a long time, TiO2 has played a lead role as a photoanode, owing to its low photo-corrosion and excellent optical as well as electrical properties, among various semiconductor metal oxides such as Nb2O5, SnO and ZnO. Hence, the present review is focused on TiO2 based photoanodes, including zero dimensional (0-D), one dimensional (1-D), two dimensional (2-D) and three dimensional (3-D) nanostructures for DSSCs. The assessment of TiO2 nanostructure based photoanodes has been comprehended in correlation to different photovoltaic parameters of the developed respective DSSCs with PCE values ranging from 1.01% to 34.5%. The conclusive properties of an efficient photoanode along with the related motivation have been stated and screen printed nanocrystalline mesoporous TiO2 film based photoanodes are found to be most suitable to design a proficient DSSC.